It is well known that there is a worldwide shortage of fresh water. One solution to this problem is large scale desalination of sea water. However, conventional desalination systems are expensive, exhibit high energy consumption and are relatively inefficient.
For example, the distillation system taught in Kruse U.S. Pat. No. 4,594,362 does not make use of the heat consumed during evaporation of saline water by regaining it during condensation, significantly lowering efficiency.
Another system is disclosed in Eidelberg U.S. Pat. No. 4,151,046 which utilizes water vapor conducted from under a metal plate to a condenser. There is no provision for the induction of ambient air or water vapor to an airspace above a sea water containment panel which, like Kruse, comprises efficiency.
The patent to Green U.S. Pat. No. 4,131,513 does not disclose the use of an insulation perimeter to reduce loss of heat or the use of heat obtained solely from a solar source.
The patent to Miller U.S. Pat. No. 2,413,466 discloses a collector that collects fresh water but does not teach the use of a collector which condenses water vapor and regains the heat of condensation by transferring it to the surrounding salt water.
Accordingly, there is a need for a cost effective energy efficient system for producing fresh water from sea water or the like.
The solar distillation system of the present invention stores solar energy in sea water in the form of heat. The system utilizes the accumulated solar generated heat as well as the heat of condensation to increase the temperature of saline water internally of perimeter insulation surrounding a plurality of integrated solar cells.
More specifically, the solar distillation system of the present invention comprises multiple solar cells, the number of which is dictated by the required output of the system. The solar cells are joined to one another and to a network of heat exchangers, vacuum lines and fresh water collection conduits disposed below the surface of a body of sea water. The bulk of water vapor condensation takes place under the surface of the body of water. The solar cells are designed so that the upper extremities thereof float above the water level while the water vapor condensation and fresh water collection portions of the systems are submerged. The entire system is insulated from the adjoining body of sea water and is designed to move up or down with the tide. System position is maintained against change in the direction of water currents and/or wind by mooring cables.
The solar still of the present invention is different than known systems in many important respects, namely; (a) the system works day and night, during cloudy days and during the cold winter season due to the fact that heat is stored in the system. Temperatures approaching 100xc2x0 C. are reached in the upper layers under the cells after four months of operation; (b) except for a means to produce a partial vacuum, there is no source of energy or equipment required to heat, circulate, or condense water vapor to produce fresh water other than solar energy; and, (c) the system is designed to produce huge quantities of fresh water out of saline water.
The aforesaid advantages are achieved by;
(1) Continuously heating the saline water to temperatures approaching the boiling point of saline water;
(2) Condensing water vapor in a collection system deep under the solar cells, for example, 40 feet;
(3) Storing heat in massive quantities at temperatures ranging from sea temperature to the boiling point of saline water;
(4) Eliminating the requirement for a pump, heating element or condenser coil;
(5) Utilizing the heat of solar radiation plus heat of vaporization;
and,
(6) Utilizing humid air above the installation which is drawn into the system.